Compare to previous AMD X4 640. I3-540 performance is lower about 10~25% in many multi-core benchmark.
On the other hand, Spuer PI, CPUMARK for single core performance, it’s higher around 18~20%.
Windows Experience Index 7.3 is same. PCMark Vantage, i3-540 is higher 2%.
X4 640 4C/4T compares to i3-540 2C/4T, the performance is different by benchmark software identity.

Temperature
System Idle - 31~32

CPU Full Speed - 52~57
Intel Burn Test v2.4，Stress Level Maximum

The latest 32nm manufacture is really helpful for the temperature.
Even though the original cooler is thin, the full speed temperature is still under 60.
After enabling C1E, the temperature even goes lower. The idle status is only 19~22. Core i3 is very good at idle temperature.